Experimental Investigation of Transmission Coefficient of Reef Breakwaters

A reef breakwater is a low crested, rubble mound breakwater without a conventional multilayered cross section. The performance of reef breakwaters has not been well researched in the past and the available research studies also do not produce conclusive results that could be used as design guidelines of these structures. It has been identified that transmission coefficient is one of the main parameters to quantify the performance of reef breakwaters. Accordingly, comprehensive laboratory investigations were carried out to study the transmission coefficient of reef breakwaters by varying different influence parameters. It was observed that wave steepness, crest width and depth of crest submergence are the most influential parameters on the transmission coefficient. The experimental data gathered from this study was used to check the performance of the existing equations developed to estimate the transmission coefficient of reef breakwaters. When using existing equations for the same input parameters, the estimated transmission coefficients appear to vary significantly from each other and hence, their applicability to real life problems is questionable. Therefore, an improved formula was developed to estimate the transmission coefficient of reef breakwaters using dimensional analysis that incorporates more influential parameters than those used in the existing equations. This formulation proved to be better than the previous equations.